Find incoming call's IMSI [closed]

Question

I am trying to find out if there is a way to detect the IMSI # of a phone that is calling you. So say for example, caller A calls person B- person B wants to know A's imsi #. I thought I read this information is transmitted to the MSC- is there a way to ask the MSC for that information?

Answer 1

An IMSI number (International Mobile Subscriber Identity) is a unique number that is private.

It is not sent to other phones, a randomly generated TMSI is sent instead.

This is because the IMSI number could be used in forging SIM cards and eavesdropping on phone calls. It is not possible to obtain the IMSI by any normal procedures and doing so would be illegal.

Answer 2

I'm not 100% agree with previous answer. Yes, it is impossible to obtain IMSI of the phone calling you. Pairs IMSI - MSISDN (phone number) pair are stored in the HLR.

But it isn't illegal to obtain IMSI by normal procedures. If you have physical access to the card you can just read EF IMSI. It isn't protected at all. Probably prev. author mentioned that it would be illegal to obtain IMSI of remote phone. If so, yes, it would be illegal because you'll need to have an access to MNO's servers.